computed.md

computed(props)(callback)

To have more control over your computed values, you can use the faker.computed() method. computed() is a special method Helix has extended onto Faker.js, and isn't available in the default Faker.js library.

Note: faker.computed() has been deprecated. Please use derived() instead.

Arguments

Argument	Type	Description
props	object	Shape of the Faker fixture data you want to compute.
callback	function	Callback function that allows you to work with the Faker rendered data.

Returns

Any: Returns whatever you determine in the callback function.

Example

The faker.computed() method accepts a single argument (object), that contains a shape of the data you'd like to work with. In the example below, we're only using name. You can add as many as you want (and nest as deeply as you want).

import { createSpec, faker } from "@helpscout/helix";

const props = {
  name: faker.name.firstName(),
};

After you pass the props into faker.computed(), instantiate a curried function with an argument of values (or whatever you'd like to name it). The values argument is your props object remapped with Faker generated content!

faker.computed(props)((values) => {
  // values is…
  // {
  //   name: 'Abigail'
  // }
});

The last step is to return whatever content you want for your computed value. In this example, we'll take our Faker generated firstName, make it all uppercase, and add a space between every letter.

faker.computed(props)((values) => {
  return values.name.toUpperCase().split("").join(" ");
});

The complete example looks something like this:

const Dinosaur = createSpec({
  id: faker.datatype.number(),
  fullName: faker.computed(props)((values) => {
    return values.name.toUpperCase().split("").join(" ");
  }),
});

Dinosaur.generate();
// {
//   id: 324191,
//   fullName: 'A B I G A I L'
// }